The use of dish antennas to receive television signals from satellites for personal use has become quite common. There are numerous satellites which relay television signals from ground located antennas to "dish" antennas located at an individual's home or other location for the private use of the television-receiving public. There are in excess of 30 satellites which orbit the earth approximately 23,000 miles in a stationary orbit about the equator. To receive the signals from the satellite, the homeowner's dish antenna must be aligned with the precise location along the equator of the particular satellite from which the television viewer desires to receive a signal . Each of the satellites will transmit or relay a number of different signals, and each satellite will normally include up to 24 transponders to relay up to 24 signals. Approximately 18 of the satellites using from 5 to 20 of the transponders provide the bulk of television transmission normally viewed by home viewers.
Since more than one satellite transmits signals which are of interest, the home viewer's television dish antenna must be moved from one position to another to align the dish with the particular satellite from which the viewer wishes to receive a signal. This reception is accomplished, therefore, by mounting the satellite dish on a mounting system which includes a polar mount; that is the satellite dish is mounted on a frame which rotates about an axis which is oriented parallel to the axis of rotation of the earth. Depending on the latitude of the location of the dish, the dish is oriented so that when rotated about the polar axis, the dish will scan along the equator upon which the various satellites are located. The satellite dish can, therefore, move from alignment with one satellite to another, each of the satellites being positioned at some point upon the equator approximately 23,000 miles out in space.
In the early days of satellite dish reception, the dish was moved manually from one satellite position location to another and this, of course, was at best a haphazard operation. More recently, powered automatic systems rotate the satellite dish about the polar mounting axis and various internal control devices automatically position the satellite dish to the optimum location.
These powered automatic systems all employ what is known in the art as an actuator. The actuator is basically a jack-type device which is connected or mounted on the frame at one point and at another upon the stationary portion of the mount. These jacks normally include a telescoping-type construction which includes a motor that operates a screw which in turn engages a nut that is attached to the inner tube of the telescoping actuator. The motor and screw assembly are located at one end of the outer tube of the telescoping assembly and thus operate the jack device.
Operation of the motor in one direction or the other will activate the screw device to move the telescoping inner tube either toward or away from the motor. Thus, the inner tube slides inwardly and outwardly within the outer tube of the jack or actuator construction and, being attached to the dish frame, will rotate the dish about the polar axis upon which the dish is mounted. In the trade, this polar axis is also called the "dish axis".
In all constructions of which I am aware in the prior art, the inner tube of the actuator is connected by a pivotal mount of a universal type to the dish frame and the outer tube of the actuator is attached to the stationary mount of the satellite dish mounting system. This stationary mount normally includes a vertical post and the outer tube is attached to this by a plurality of bracket members, which are attached to the stationary frame which is a part of the vertical post.
Because of the manner in which the actuator is attached both to the stationary mounting assembly and the dish frame which is movable about the polar axis, and the dish being positioned at an angle to scan the equator, the actuator is angled upwardly the proper number of degrees depending upon the latitude of the location of the receiver.
As the satellite dish is moved from one position to another so that the signals from different satellites may be received, the inner tube of the actuator mechanism slides inwardly and outwardly within the outer tube of the actuator mechanism. After a period of time wear, caused by this constant inward and outer motion of the inner tube, permits various weather elements such as rain, sleet and snow to enter the jack mechanism. In an attempt to prevent problems from occurring, actuators include drainage holes in the motor and gear box housing so that this moisture can be drained from the mechanism. The provision of drainage holes normally will prevent problems from occurring; however, in actual practice, after a period of time, because of the wear, caused by the continual inward and outward movement of the inner tube member of the telescoping construction, as well as the accumulation of dirt and other foreign matter, a situation will exist in which moisture will accumulate within the gear box and telescoping tube members of the actuator.
When this happens, at locations where freezing temperatures are encountered, the accumulated moisture will freeze and prevent movement of the actuator or cause damage to either the gears which operate the screw or the screw device itself.
Under such conditions, the actuator must either be repaired or thawed to allow proper actuator operation. Efforts to alleviate the problems have included the provision of a weather resistant rubber boot which is placed around the outer exposed end of the outer tube at the position where the inner tube slides inwardly and outwardly in the outer tube. These boots, while being an improvement over no protection, are less than satisfactory and the actuators are still subject to the same problems of moisture accumulation primarily because of the wear to the boot caused by the continual inward and outward movement of the inner tube as the actuator moves or rotates the satellite dish from one position to another.
U.S. Pat. No. 4,918,363 discloses a typical example of the prior art devices which are subject to the aforementioned problems. The device disclosed in this reference includes an electrically powered motor which drives a series of gears that turns a worm gear assembly to move an inner telescoping member within an outer telescoping member to either elongate or shorten the actuator length, thereby rotating the satellite dish about a polar axis so that the dish may be aligned to a desired satellite position. The actuator or jack disclosed in this reference shows the motor and gear assembly mounted within housing members and located at the lower end of the jack. As seen in FIG. 1 of this reference, as the motor turns the worm gear assembly, the inner tubular member is moved inwardly or outwardly and the dish is thereby rotated. As can be seen in FIG. 8 of this reference, the juncture between the inner and outer tube appears to be protected by the aforementioned rubber boot. However, because of the jack's positioning, as shown in FIG. 1, moisture will eventually enter the interior of the telescoping tube construction and likewise enter the gear box area with the resulting problems associated with the moisture freezing.
Accordingly, there is an unsatisfied need for a satellite actuator or jack mounting construction which will eliminate the problems caused by the accumulation of moisture within the interior of the telescoping jack. It is, therefore, a primary object of the present invention to provide a jack mounting construction which is not susceptible to problems caused by the accumulation of moisture within the interior of the actuator construction.
It is a further object of the present invention to provide a satellite antenna actuator mounting construction in which the motor or drive system of the jack is mounted directly to the satellite dish frame, and in which the inner tubular telescoping member of the construction is attached to the upright support member whereby the open end of the outer actuator tubular member, through which the inner tubular member passes, faces downwardly to prevent the accumulation of moisture within the interior of the jack construction.
It is a further object of the present invention to provide a mounting bracket for attaching the housing end of the actuator construction directly to the frame of a satellite dish.
These and other objects and advantages will be apparent from the construction of the mounting mechanism of the present invention, the general nature of which may be stated as a power driven telescoping actuator construction having a housing enclosing a motor and gear mechanism, an outer tubular member extending from said housing, a gear member connected to an inner tubular member which is extendible and retractable, said housing end of said outer tubular member being attached to the frame of a satellite dish which is pivotally mounted on a polar axis and the outer end of the inner tubular member being attached to an upright dish support member whereby extension or retraction of the inner tubular member within the outer tubular member will rotate the satellite dish about the polar axis.